Narrative:

Shifted from ILS 25L to visual 25R on approach to lax. Commuter vectored from south for visual to 25L. Received TCASII RA to climb at approximately 2500 ft. All red except 3 green dots at the top, visual presentation went from -300 ft rapidly to 0 ft, initiated climb and right turn (since target was in 8 O'clock position and knew aircraft was being vectored in from the left). Thought I might be descending on top of him. Was warned by lax tower that aircraft was to right on approach to north complex. The aircraft on approach to 25L had me in visual contact. Discontinued climb, reestablished descent, silenced the TCASII as it was very loud and distracting. (Violates the spirit of the sterile cockpit.) had the I.O. Look out left window, advised that there was an aircraft on our left wing. I observed a commuter aircraft flying formation on my left wing, less than 2 wing lengths away, stepped up 30 ft maximum. This was not a safe maneuver! Continued approach and landed. The software in the TCASII is obviously if/then. It should also take into consideration location and environment. In other words, an expert system or better yet use the expert system of the flight crew. Put a shutoff button like the altitude alert. My primary concern was the sfra over lax which is full of VFR traffic, not expecting an airliner coming through at 90 degree to their direction of flight.

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Original NASA ASRS Text

Title: CLOSE PROX ACR-WDB COMMUTER-LTT ON PARALLEL APCH TO RWYS 25 AT LAX.

Narrative: SHIFTED FROM ILS 25L TO VISUAL 25R ON APCH TO LAX. COMMUTER VECTORED FROM S FOR VISUAL TO 25L. RECEIVED TCASII RA TO CLB AT APPROX 2500 FT. ALL RED EXCEPT 3 GREEN DOTS AT THE TOP, VISUAL PRESENTATION WENT FROM -300 FT RAPIDLY TO 0 FT, INITIATED CLB AND R TURN (SINCE TARGET WAS IN 8 O'CLOCK POS AND KNEW ACFT WAS BEING VECTORED IN FROM THE L). THOUGHT I MIGHT BE DSNDING ON TOP OF HIM. WAS WARNED BY LAX TWR THAT ACFT WAS TO R ON APCH TO N COMPLEX. THE ACFT ON APCH TO 25L HAD ME IN VISUAL CONTACT. DISCONTINUED CLB, REESTABLISHED DSCNT, SILENCED THE TCASII AS IT WAS VERY LOUD AND DISTRACTING. (VIOLATES THE SPIRIT OF THE STERILE COCKPIT.) HAD THE I.O. LOOK OUT L WINDOW, ADVISED THAT THERE WAS AN ACFT ON OUR L WING. I OBSERVED A COMMUTER ACFT FLYING FORMATION ON MY L WING, LESS THAN 2 WING LENGTHS AWAY, STEPPED UP 30 FT MAX. THIS WAS NOT A SAFE MANEUVER! CONTINUED APCH AND LANDED. THE SOFTWARE IN THE TCASII IS OBVIOUSLY IF/THEN. IT SHOULD ALSO TAKE INTO CONSIDERATION LOCATION AND ENVIRONMENT. IN OTHER WORDS, AN EXPERT SYS OR BETTER YET USE THE EXPERT SYS OF THE FLC. PUT A SHUTOFF BUTTON LIKE THE ALT ALERT. MY PRIMARY CONCERN WAS THE SFRA OVER LAX WHICH IS FULL OF VFR TFC, NOT EXPECTING AN AIRLINER COMING THROUGH AT 90 DEG TO THEIR DIRECTION OF FLT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.